As a thermistor material which may be employed at higher temperatures, (a) a material mainly composed of a corundum type crystal structure, as disclosed for example in JP Patent KOKAI Publication No. 50-118294 (JP-A-118284/75) or in "Fine Ceramic Handbook" by K. Yano, published by ASAKURA SHOTEN in 1984; (b) a material mainly composed of a compound having a spinel type crystal structure, as disclosed for example in JP Patent KOKAI Publication No. 48-63985 (JP-A-63995/74), (c) a material mainly composed of zirconia, as disclosed in, e.g., "Nainenkikan" (Internal Combustion Engine) vol 30, No. 8, page 98, and (d) a material mainly composed of a compound having a perovskite type crystal structure.